The research proposed herein seeks an understanding of the role of the visual climbing fiber (CF) pathway to the flocculus of the cerebellum in the control of eye movement. The technique of extracellular single unit recording will be used to record the activity evoked in single floccular Purkinje cells be optokinetic (OKN), neck proprioceptive, and vestibuloocular reflex (VOR) activation, in unanesthetized rabbits. The visual stimulus will be servo-controlled by feed-back of eye position so that the retinal slip velocity of the OKN stimulus can be "clamped". The possible role of CF evoked Golgi cell inhibition in cerebellar function will be examined. The effect of constant retinal slip velocity on the activity of cells in the medial vestibular nucleus will be examined. The parameters of OKN stimulation which induce long term changes in the VOR will be specified both behaviorally and electrophysiologically. Projections of the flocculus and other visual pathways onto the vestibular nuclei will be studied.